1. Field of the Invention
The present invention relates to a receiving apparatus and method in a wireless communication system. More particularly, the present invention relates to an apparatus and method for canceling neighbor sector or cell interference in a broadband wireless communication system.
2. Description of the Related Art
In general, mobile wireless communication systems were developed for the purpose of providing voice service. Over time, such wireless communication systems have been further developed to also provide packet data service and various multimedia services as well as voice service. Because the systems that can provide a wireless packet data service as described above were realized during a third generation of system development, they are known as 3rd-Generation (3G) mobile communication systems. The 3G mobile communication systems have been further developed to provide a diversity of multimedia services at high speed. The 3G mobile communication systems distinguish users using a Code Division Multiple Access (CDMA) scheme. The CDMA scheme distinguishes channels by allocating a different code to each user such that each code is orthogonal to codes transmitted to other users.
However, the 3G mobile communication systems are limited in that they cannot provide higher-speed data with high quality because of a shortage of codes, etc. That is, a transmission rate is limited because the number of available codes is limited. To address this limitation, research and development is currently underway on 4th-Generation (4G) broadband wireless communication systems which are so-called future-generation communication systems. The 4G broadband wireless communication systems can classify users or channels using an Orthogonal Frequency Division Multiple Access (OFDMA) scheme. With these advanced features, the 4G broadband wireless communication systems can increase a transmission rate up to about 100 Mbps. Thus, the 4G broadband wireless communication systems can provide services having more diverse Qualities of Service (QoS) than the 3G systems.
Current 4G communication systems have been developed to ensure mobility and QoS in Broadband Wireless Access (BWA) communication systems such as wireless Local Area Network (LAN) systems and wireless Metropolitan Area Network (MAN) systems. Their typical communication systems can be Institute of Electrical and Electronics Engineers (IEEE) 802.16d communication systems and IEEE 802.16e communication systems, for example. In addition, various types of systems using an Orthogonal Frequency Division Multiplexing (OFDM) scheme have been developed.
As described above, a broadband wireless communication system can basically use the OFDMA scheme, ensure mobility, and allow all cells to use the same frequency to enhance frequency efficiency.
FIG. 1 is a schematic diagram illustrating a conventional multi cell based BWA system.
Referring to FIG. 1, in a conventional multi cell system, a serving Base Station 0 (BS0) 100, a neighboring BS1 101, and a neighboring BS2 102 perform communication using the same frequency. That is, the multi cell system has a frequency reuse factor of 1 and can therefore enhance frequency efficiency. However, such frequency reuse may also suffer fatal degradation of performance because of inter-cell or inter-sector interference.
For example, when a Mobile Station (MS) 103 in the serving BS0 100 is considered, transmitted signals from an MS 104 in the neighboring BS1 101 and transmitted signals from an MS 105 in the neighboring BS2 102 act as interference signals to the serving BS0 100. That is, the serving BS0 100 receives not only a received signal 106 from the MS 103 in a corresponding cell but also interference signals 107 and 108 from the MS 104 in the neighboring BS1 101 and the MS 105 in the neighboring BS2 102, respectively. The interference signals from the neighbor cells have an influence upon the signal of the MS 103 in the corresponding cell, thus deteriorating demodulation performance. Thus, the multi cell based BWA system requires a technique for canceling neighbor cell or sector interference.